The present invention relates to an improved metal plating method and apparatus, and more particularly relates to improvements in high speed metal plating system in which application of large current at low voltage causes relative movement between electrolyte and a workpiece to destroy an ion diffusion layer on the surface of the workpiece.
Such a conventional high speed metal plating system generally includes a pretreatment unit, a metal plating unit and an aftertreatment unit which are arranged one after another along a straight path. The system is further provided with a transfer unit which transfers workpieces through each unit and form units to unit. Each workpiece is loaded to the system at a supply port of the pretreatment unit for travel through various treatment baths in the unit being carried by the transfer unit. On arrival at the metal plating unit, the workpiece is accommodated in a metal plating bath in the unit. Under application of large current at high voltage, the bath, i.e. the electrolyte, is forced to flow at a high speed for plating of the workpiece. Next, the plated workpiece is passed through various treatment baths in the aftertreatment unit for final unloading at a discharge port of the aftertreatment unit.
Since the processing speed of the system is freely adjustable, the system can be well incorporated into a continuous line of production. Despite this advantage, the straight arrangement of the three units requires reservation of a large spacing in the continuous line of production. Further, in the case of the conventional high speed metal plating system, no special expedients are taken into consideration for efficient transfer of workpieces between the system itself and associated systems. Thus the production efficiency of the entire production line is ill influenced by presence of such a neck of transfer between the associated systems.